the SIL Open Font License is considered to be a special purpose Free
  Software License (on the FSF list) for fonts. Due to the special nature,
  it differs from GPL and BSD license in a number of areas, one critical
  difference being that selling the font alone is prohibited. It is

This is odd, but

  permitted to sell aggregated work containing such a font though.

to me, the key point is that it is approved by the FSF.

  I don't think this warrants any NO_*_ON_* and I don't think it warrants
  requiring special acceptance, so I would like to add it to the default
  list of acceptable licenses.

I agree, and I think you should go ahead and add it.